Insulation containing inorganic fiber and spherical additives

ABSTRACT

The present invention provides thermal insulation products such as loose fill, batts and boards, such as duct boards and duct liner. The insulation products include randomly distributed inorganic fibers, which are supplemented with at least about five weight percent microspheres, macrospheres, or both, and preferably include hollow microspheres, which boost the insulation value of the fiberglass thermal insulation by at least about 0.5R.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.11/195,055, filed Aug. 2, 2005, which is a continuation-in-part of U.S.application Ser. No. 10/869,994, filed Jun. 17, 2004 now abandoned.

FIELD OF THE INVENTION

The present invention relates to insulation products, and morespecifically to loose fill insulation, batts and board products andmethods of making the same.

BACKGROUND OF THE INVENTION

Thermal insulation for buildings and other structures is available inthe form of mats, batts, blankets and loose fill. Mats, batts andblankets are flexible products containing randomly oriented fibers boundtogether with a binder, and are generally prefabricated before beingbrought to a construction site and installed. In contrast, loose fillthermal insulation includes a large number of discrete fibers, flakes,powders, granules and/or nodules of various materials. The loose fillcan be poured or blown into hollow walls or other empty spaces toprovide a thermal barrier.

Because of cost-effectiveness, speed and ease of application, as well asthoroughness of coverage in both open and confined areas, the practiceof using pneumatically delivered or “blown” loose-fill insulationmaterials, e.g., glass fiber, rock wool, mineral fiber wool, cellulosefibers, expanded mica, and the like, has become an increasingly popularmethod by which to install insulation in new and existing buildingconstructions.

Loose-fill insulation blown into attics, basements and outside wallcavities is very effective in reducing heat transfer in existingbuildings. Loose-fill insulation can provide a substantial advantageover batt-type insulation in that the loose-fill material readilyassumes the actual shape of the interior cavity being filled, whereasthe insulative batts are manufactured in a limited number of standardsize widths, none of which will as closely match the actual dimensionsof wall cavities or accommodate obstructions encountered in the field.Properly installed, loose-fill insulation essentially completely fills adesired area of the building cavity, conforming to the actual shape ofthe building cavity, including obstructions, such as water, waste andgas lines, electrical conduits, and heating and air conditioning ducts,and provides, in that respect, effective resistance to heat transferthrough walls, floors or ceilings.

Any insulation that is capable of compression has an expanded volume dueto included air, within spaced apart, fibers or particles or foam ofmaterials such as glass, polymer or cellulose. An industry standardR-value is a rating number that is printed on the insulation. TheR-value refers to the extent to which the insulation reduces the rate ofheat transfer through the insulation. The R-value typically increaseswith increases in thickness and with increases in density of theinsulation for a given material. When the insulation is installed, it iscapable of compression to fill a building cavity having a width, forexample, on 12 inch centers, 16 inch centers, 17.7 inches or 24 inchcenters. Further, the insulation is capable of compression to fill thecavity having a length defined by the width of either 9.5 inches for a2×10 joist, or 11.5 inches for a 2×12 joist, or 13.5 inches for a 2×14joist, or 15.5 inches for a 2×16 joist. Such a compression is in adirection transverse to the R-value and thickness, which would notsubstantially reduce the R-value of the insulation.

While insulation products based upon glass fibers are known, there isstill a need to improve the thermal efficiency, “R”, of such products ina cost effective manner.

SUMMARY OF THE INVENTION

In the first embodiment of the present invention, a fiberglass thermalinsulation is provided which contains about 50-95 weight percent ofrandomly distributed inorganic fibers and about 5-50 weight percentmicrospheres. The microspheres boost the insulation value of thefiberglass insulation by at least about 0.5 R.

The present invention can provide fiberglass insulation products such asloose fill insulation, batts or duct boards, for example. When the glassmicrospheres, preferably hollow microspheres are added to blown loosefill insulation, the thermal performance can be boosted at least about0.5 R by as little as 5 weight percent of hollow microspheres.

Hollow glass microspheres, such as those provided by 3M in the form ofbrand names K1, K20 and K25, have a density of about 0.125 g/cc-0.60g/cc and a size of about 12-300 microns, preferably about 30-120microns. Both plastic or inorganic, such as glass or ceramic,microspheres can be used.

In the further embodiment of the present invention, an insulation battor board is provided which includes a fiberglass thermal insulationlayer containing randomly distributed inorganic fibers, and at least 5weight percent microspheres, the microspheres boost the insulation valueof the fiberglass insulation batt or board by at least about 0.5 R. Theinsulation layer is joined to a facing layer, such as Kraft paper, or apolymeric layer, such as polyethylene film. In a variation of thisembodiment, the microspheres can be adhered to a layer of the insulationlayer, such as by applying the microspheres to the bituminous masticused to join the facing to the insulation layer, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of theinvention, as well as other information pertinent to the disclosure, inwhich:

FIG. 1 illustrates loose fill insulation blown in an attic between apair of joists; and

FIG. 2 illustrates an insulation batt having microspheres in threedifferent locations.

DETAILED DESCRIPTION

Loose Fill

FIG. 1 illustrates loose fill insulation 12 blown in an attic 14 betweena pair of joists 13, 13. With reference to FIG. 1, a loose fillinsulation product 10 having microspheres 11 dispersed therein isprovided. The loose fill insulation 12 can be in the form of fibers,flakes, powders, granules and/or nodules of various materials. The loosefill insulation is of the type for insulating an interior of a hollow oropen space in a building structure, e.g., a house, office, or otherbuilding structure. Preferably, the loose fill can be compressed duringstorage to save space, and then expanded or “fluffed-up” with air oranother gas when poured or blown into a hollow wall or other empty spaceof a structure. The loose fill insulation 12 can include organicmaterials, inorganic materials or both. Examples of organic loose fillmaterials include animal fibers, such as wool; cellulose-containingvegetable fibers, such as cotton, rayon, granulated cork (bark of thecork tree), redwood wool (fiberized bark of the redwood tree), andrecycled, shredded or ground newspaper fibers; and thermoplastic polymerfibers, such as polyester; and expanded plastic beads. Examples ofinorganic loose fill materials include diatomaceous silica (fossilizedskeletons of microscopic organisms), perlite, fibrous potassiumtitanate, alumina-silica fibers, microquartz fibers, opacified colloidalalumina, zirconia fibers, alumina bubbles, zirconia bubbles, carbonfibers, granulated charcoal, cement fibers, graphite fibers, rockfibers, slag fibers, glass wool and rock wool. The loose fill caninclude one or more varieties of loose fill material. In an exemplaryembodiment, the loose fill insulation includes OPTIMA® fiberglass loosefill insulation available from CertainTeed Corporation, Valley Forge,Pa.

When manufactured and compressed during storage, the loose fillparticles forming the compressed loose fill are dimensioned so as tohave an equivalent sphere with a diameter generally smaller than 3 cm,preferably from 0.1 to 1 cm. In one embodiment, after the compressedloose fill is decompressed, expanded and processed through a blowinghose, the loose fill particles forming the expanded loose fill are eachdimensioned so as to just fit within a sphere having a diameter of from0.1 to 4 cm, preferably from 0.5 to 2 cm.

The thermal insulation product including the microspheres 11 can beformed by dispersing, preferably uniformly, the microspheres 11 in theloose fill 12 before or at the same time as the loose fill is poured orblown into an interior, empty space of a hollow or open object, such asa hollow wall (before application of the drywall) or an attic. Methodsof pouring and blowing loose fill 12 are well known in the art and willnot be repeated here in detail. Generally, blowing loose fill 12involves feeding compressed loose fill 12 into a blower where it ismixed with a gas, such as air, expanded, processed through a blowinghose, and then blown into a hollow or open structure to form thermalinsulation.

In certain embodiments, a mixture including one or more microspheres 11,such as hollow plastic and glass microspheres, and a dry binder (i.e.,an adhesive later activated by water at the time of installation of theloose fill) can be sprayed onto or otherwise mixed with the loose fill10 before the loose fill 10 is compressed and/or when the loose fill 10is decompressed. Also, a mixture including one or more microspheres 11and a binder (i.e., an adhesive) can be mixed with the loose fill byspraying on the loose fill at or near the end of the blowing hose beforethe loose fill is installed in a hollow or open space wherein saidhollow microspheres are permitted to settle through said randomlydistributed inorganic fibers so as to concentrate on a lower portion ofsaid cavity. The binder serves to join and hold the microspheres 11 andthe loose fill insulation together. The binder can be organic orinorganic. The organic binder can include an organic water based bindersuch as an acrylic latex or a vinyl acetate latex. The organic bindercan also include a sprayed hot melt adhesive such as a thermoplasticpolymer. The inorganic binder can include an inorganic bonding agentsuch as sodium silicate or a hydraulic cement. Evaporation of the liquidfrom the liquid mixture on the loose fill 10 results in a loose fillthermal insulation 10 with the microspheres 11 and/or binder dispersedin the loose fill 10. In various embodiments, the microspheres 11 andthe binder can be added to the loose fill 10 at the same time or atdifferent times. A mineral oil can be used instead of or in addition tothe binder for the purpose of dust reduction. In other embodiments,rather than providing the microspheres 11 in a liquid mixture, themicrospheres 11 may be provided to the loose fill 10 in its liquidslurry state or as a powder and, optionally, along with a mineral oiland/or binder as described above.

In one preferred embodiment, loose fill insulation is fed through aloose fill transport duct into mixer to form a mixture of loose fill 12and microspheres 11. The microspheres 11 may be provided, for example,in slurry or dry form. In embodiments, a dry binder (to be lateractivated by water or other material during loose fill application)and/or mineral oil can also be added in the loose fill transport duct oradded in and mixed in mixer with the loose fill and phase changematerial. The phase change material can be added directly to the mixerand/or to the loose fill transport duct. The mixture is then fed tocompressor/packager, where the mixture is compressed to remove air andincrease density and packaged as compressed loose fill including themicrospheres.

Microspheres

Microspheres are small solid or hollow spheres with an average diameterin the range of 12-300 microns, preferably about 15-200 microns, andmost preferably about 30-120 microns. Microspheres are commonly made ofglass, and are desirably made hollow for their thermal and soundinsulation qualities. Borosilicate or similar glass is preferred becauseof its insolubility in water. Alternatively, recycled amber containerglass frit is also attractive, since it can be made into hollow glassamber spheres, without the addition of a sulfur-containing compound,since sulfur is a pre-existing constituent. A number of glassmicrosphere grades are available, in a range of wall thicknesses,strengths, and densities from under 10 pcf to over 20 pcf, preferablyabout 0.125-0.60 g/cc.

Fiberglass macrospheres were created to overcome some of the limitationsof glass microspheres. As their name suggests, macrospheres arerelatively large, with most common diameters in the 0.125″-0.500″ range.A wide selection is available of strengths and densities, in roughly thesame range as glass microspheres. Macrospheres increase the overallpacking factor to 70% or more, and are often less expensive than glassmicrospheres.

As the name implies, microspheres are small, spherical particles.Particle sizes range from 12 to 300 microns in diameter, and wallthickness can vary from several microns to as low as 0.1 micron. Theycan be composed of acrylonitrile, glass, ceramic, epoxy, polyethylene,polystyrene, acrylic, or phenolic materials. Because they are hollow,the true density of microspheres is lower than that of other non-solubleadditives. The true density of hollow microspheres ranges from 0.60 g/ccto as low as 0.025 g/cc.

There are many potential applications for hollow glass microspheres.Sodium borosilicate hollow microspheres are often used as light-weightfillers of composite plastics for ship-building, aviation and car-makingindustries, sensitizing additives in manufacture of industrialexplosives, varnishes, and paint fillers. In contrast to mineral andorganic fillers, hollow microspheres are unique because they have a lowdensity but high strength.

The production of hollow microspheres is a well-established technology.There are several methods available to produce hollow microspheres, butevery approach depends on the decomposition of a substance known as a“blowing agent” to form a gas within in a liquid. The rapid expansion ofthis gaseous product causes the formation of a bubble. One of the mostcommon methods for producing hollow microspheres is to intentionally mixa trace amounts of a sulfur-containing compound such as sodium sulfatewith a sodium borosilicate glass that is similar in composition totraditional PYREX® glassware. This mixture is then dropped into a hotflame that melts the powdered glass and sodium sulfate. The melting ofsodium sulfate results in a decomposition reaction that releases minuteamounts of sulfur gas that form bubbles within the molten glassdroplets. (Sodium sulfate additions are not necessary when waste orvirgin amber glass frit is used, since sulfur-containing compounds aremainly responsible for the amber color of the glass and are alreadypresent.) The hollow droplets are then rapidly cooled from the liquidstate to form hollow microspheres. As previously mentioned, such anapproach relies on the intentional addition of a sulfur-containingcompound to the glass.

Microspheres have found use in many applications over the years. Theyare widely used in the fiber-reinforced polyester industry to improvethe manufacturing process of shower stalls and boats. Lighter,more-durable fiberglass products are a direct result of the creative useof microspheres. Thick-film ink, mining explosives, and rubber andplastic products of all descriptions are just a few other examples ofthe many products that are made better with these versatile materials.The benefits derived by these diverse end uses vary—some are unique to aspecific industry, while others are common goals shared by manymanufacturers.

Likewise, certain types of microspheres may offer a particular set ofadvantages, and a formulator must carefully select from the manyproducts available in order to obtain the best results. For example, thecompressible nature of plastic microspheres is a unique feature that issuited to elastomeric products, while glass microspheres are ideal forareas involving high temperatures and/or chemical resistance.

Plastic Microspheres

Developed in the 1970s, thermoplastic microspheres are compressible,resilient, hollow particles. The extremely thin shell wall possible withplastic spheres results in specific gravities as low as 0.025 and allowsjust a small weight-percent of these materials to displace large volumeswhen disposed in matrices. Because the resilient plastic can deformunder stress, there is virtually no breakage when mixing or pumpingthese products, even with high shear mixing, as in the case of blowingloose fill insulation. Additionally, the compressible nature of plasticcan absorb impacts that might ordinarily deform the finished product,thereby reducing damage caused by stone chips, foot traffic orfreeze-thaw cycles.

Glass Microspheres

Glass bubbles were developed in the 1960s as an outgrowth from themanufacture of solid glass beads. Since they are made of glass theyprovide the benefits of high heat and chemical resistance. The walls ofglass bubbles are rigid. Products are available in abroad range ofdensities from as low as 0.125 g/cc to 0.60 g/cc. The collapse strengthof the glass bubble is directly related to the density, i.e., the higherthe density, the higher the strength. For example, a glass bubble with adensity of 0.125 g/cc is rated at 250 psi, whereas one with a density of0.60 g/cc is rated at 18,000 psi. In order to minimize both the cost andthe weight of the final product, the appropriate glass bubble is the onethat is just strong enough to survive all of the manufacturing processesand the end use of the product.

Since microspheres are closed-cell, gas-filled particles, they areextremely good insulators. This characteristic is imparted to materialsthat contain microspheres, such as batts, boards and loose fillinsulation products. As this invention demonstrates, thermal andacoustic insulation properties of batts, loose fill, facings, coatingsor substrates can be improved by the addition of microspheres.

Physical Properties and Composition

The 3M Type K1 microspheres are manufactured from soda-lime-borosilicateglass and is the most economical 3M microsphere product at about $0.40per liter. TABLES 1 and 2, below, contain selected properties of Type K1microspheres. Trapped within the microspheres are residual gasesconsisting of a 2:1 ratio of SO₂ and O₂ at an absolute pressure of about⅓ atmosphere. Amorphous silica is added at 2% to 3% by weight to themicrospheres to prevent caking if exposed to water. Caking of the bulkmicrospheres is caused by bridging of residual salts from themanufacturing process that have condensed on the surface of themicrospheres. Amorphous silica, commonly used as a desiccant, has a veryhigh specific surface area. The relatively small percentage of amorphoussilica actually makes up the majority of the overall specific surfacearea and causes the bulk material to have a greater capacity foradsorbed water that must be dried out before or during the evacuationprocess. The effect on vacuum retention following exposure ofmicrospheres and perlite to atmospheric conditions without a dryingprocess prior to evacuation follows this section.

Alternative glass bubbles to the Type K1 microspheres are produced by 3Mand also by Emerson & Cuming. Options include a floating process thatskims off low density (weak) bubbles and removes a portion of thecondensed salts. A coating of methacrylaic chromic chloride is thenapplied that minimizes water pickup. The overall specific surface areais about half that of the Type K1 microspheres, which may allow reducedbake-out requirements due to lower water adsorption capacity. The use ofthicker-walled bubbles will benefit applications where microspheres areexposed to intense localized forces.

TABLE 1. Thermal performance of 3M Type K1 microspheres

TABLE 1 Thermal performance of 3M Type K1 microspheres APPARENT THERMALCOMPARATIVE COLD VACUUM CONDUCTIVITY THERMAL PRESSURE (torr) (mW/m-K)PERFORMANCE 1 × 10⁻³ 0.7 7.0 times worse than MLI 1 × 10⁻¹ 1.4 3.3 timesbetter than perlite 760 22 1.5 times better than polyurethane

TABLE 2. Selected properties of 3M Type K1 microspheres

TABLE 2 Selected properties of 3M Type K1 microspheres True density0.125 g/cc (7.8 lb/ft³) Bulk density (@ 60% packing factor) 0.075 g/cc(4.7 lb/ft³) Particle size (mean/range) 65/15-125 microns Isostaticcrush strength 1.7 MPa (250 psi) Maximum operating temperature 600° C.Specific surface area 0.2 m²/cc of bulk volumeFiberglass Thermal Insulation Batts and Boards

As shown in FIG. 2, fiberglass thermal insulation batts 20, or boards,such as duct boards, duct liners, and the like, can be manufacturedusing the materials provided by this invention. In a further embodiment,a batt 20 is manufactured with a fiberglass insulation layer 23. Thefiberglass insulation layer contains randomly distributed inorganicfibers such as glass fibers and contains about 5 weight percentmicrospheres 21 which can be randomly distributed among or on theinorganic or glass fibers 22. Alternatively, the microspheres can beadhered to the top or bottom layer of the insulation layer 23 or mixedwith an adhesive 27, such as a resinous adhesive or bituminous mastic,used to apply the facing 26 to the fiberglass insulation layer 23. Thefacing can be applied to one or both major surfaces of the insulationlayer 23, or can be applied to envelope the insulation layer 23. Stillfurther, the microspheres can be adhered or made integral with thefacing 26, such as by spraying, ink jet, printing or using a roll toapply an adhesive layer followed by applying the microspheres, orapplying the microspheres as a slurry in such a process. When applied tothe facing 26, a uniform covering of microspheres 24, 25 is desirable,but the weight percentage may be less than 5%, such as 0.5-3%, basedupon the weight of the fibers or the facing 26. Alternatively, themicrospheres may be applied to the top surface of the fiberglassinsulation 23 by use of a binder or adhesive, or concentrated in a layeror region near the surface or in the middle of the insulation layer 23.

From the foregoing, it can be realized that this invention providesimproved loose fill insulation, and batts and boards which includemicrospheres and/or for increasing the thermal insulation efficiency.The microspheres can be distributed within glass fibers, cellulosicparticles, or adhered to facing layers or glass fibers, for example, toprovide a great variety of more efficient thermal insulation products.The glass spheres of this invention also can assist in sound deadeningand may assist in allowing loose fill insulation to flow through hosesused for blowing such products into attic cavities and wall spaces.Although various embodiments have been illustrated, this is for thepurpose of describing, but not limiting the invention. Variousmodifications which will become apparent to one skilled in the art, arewithin the scope of this invention described in the attached claims.

1. An insulated attic, comprising: a plurality of joists, and a loosefill insulation between said joists, said loose fill insulationconsisting of about 50-95 weight percent glass fibers which are randomlydistributed with included air within spaced apart portions of said glassfibers, and about 5-50 weight percent insulating hollow microspheres anda binder, which provide a thermal insulation layer; said microspheresbeing settled so as to concentrate in a lower region of said thermalinsulation layer; and said binder binding together respective said glassfibers to comprise a fiberglass insulation layer having said glassfibers and said included air, and said binder binding together saidmicrospheres which are settled in said lower region with correspondingsaid glass fibers which are in said lower region.
 2. The insulated atticof claim 1, wherein said microspheres comprise glass or plastic.
 3. Theinsulated attic of claim 1, wherein said microspheres comprise soda-limeborosilicate glass, or recycled amber glass.
 4. The insulated attic ofclaim 1, wherein said microspheres comprise a diameter of about 12-300microns.
 5. The insulated attic of claim 1, wherein said microspherescomprise a density of about 0.125-0.60 g/cc.
 6. The insulated attic ofclaim 1, wherein said microspheres comprise a diameter of about 12-300microns and a density of about 0.125-0.6 g/cc.
 7. The insulated attic ofclaim 1, wherein said glass fibers and said microspheres are mixed. 8.The insulated attic of claim 1 wherein said microspheres are distributedwith said randomly distributed glass fibers in said lower region.